My initial goal for my summer research was to design an experiment for obtaining single molecule scans in oil environments of a special type of organic dye known as hydroxyanthraquinone. However, this experiment became very challenging and earlier in the summer my professor presented me with a side project that soon became the main focus of my summer research. This experiment involved recreating single molecule scans of the hydroxyanthraquinone dye alizarin with our new higher energy laser, in a polar solvent (ethanol). Previous research in our lab preformed single molecule scans using alizarin in ethanol on a lower energy laser, and I assumed this would be an easy project. However, recreating this experiment turned out to be difficult process that required the whole summer.

The summer has really flown by, and I certainly did not get as much done as I (and my advisor) had initially hoped. The goal for data collection of my work is to obtain many single molecule fluorescence scans of our dye and then conduct “blinking traces” on each individual molecule which plot the relative fluorescence intensity vs. time. We had hoped to have those all our scans finished midway through July but we had some setbacks finishing our control experiments due in part to equipment troubles. Now that my partner and I have been successful at replicating single molecule scans, we have been scrambling to collect as many blinking traces of molecules as we can before the summer ends.
Regardless, this summer was beneficial in that I was able to develop a basic understanding of the data analysis portion of our research. My project uses a Matlab code previously developed by brilliant former researchers that records the relative changes in the intensities of fluorescence in our blinking traces. It records this data as a set of values that represent the time in seconds of various types of “events” such as fluorescing (“on”) events or non-fluorescing (“off”) events. Next, we can have Matlab develop a probability distribution that represents the likelihood of a specific time of an event occurring based on the relative number of times that value occurred in the data set. Lastly, we can hope to describe the data by fitting it to various heavy-tailed distribution functions, which are used because they represent a large data set (from times as small as 10^-2 seconds to 10^3 seconds). Matlab also generates p-values for this fits to give us a better understanding of which functions fit best. I hope that when I return in the fall I can use this approach fully analyze my data and develop a better understanding of how our dye molecule behaves when exposed to our laser.

It turns out that my partner and I haven’t been as unsuccessful at finding single molecules as we thought. When we presented our data at group meeting earlier this week, we showed our single molecule dye scans from the previous week like usual. Some of our scans had a few bright distinctive molecules with high counts from our detector, while other scans only had dimmer molecules. My partner semi-joking called this “reproducible inconsistency” in our data, and we shrugged off what we thought was another week of inconclusive data.

What I have been doing this summer has been very different than what I initially expected. I started the summer attempting to study the photochemistry dye molecules in oil environments. Then, on the second day Dr. Wustholz asks my partner and I to perform some single molecule studies of alizarin dye our fancy new laser. We are hoping that the higher energy of this laser will allow us to observe some unique photochemistry that could not occur with our 532 nm laser. The data we collect might be the missing link for publishing a paper.

The preservation of artwork is often limited by the fragility of its medium; conservators must constantly be working to counteract the forces of nature. One example is the gradual fading of organic dyes in paintings, leading to a loss of their color and vitality. As a chemist, I want to get an understanding of the process of dye fading by studying the effects of exposing them to their natural friend & foe, light.